Shredder



. 17, 1935. A. F. WENDLER SHREDDER Filed April 23, 1932 2 I flilENTORAT'E'ORNEY Patented Dec. 17, 1935 UNITED STATES PATENT OFFICE SHREDDERAdolph F. Wendler, Kenmore, N. Y., assignor to Du Pont CellophaneCompany, Inc., New York, N. a corporation of Delaware Application April23, 1932, Serial No. 607,041 2.0laims. (Cl. 1f16122)- This inventionrelates to shredding, disintegrating and mixing machines, and moreparticularly to machines for shredding alkali cellulose to be employedin the manufacture of a viscose solu- 5 tion. 7

In one common method utilized for the manufacture of viscose, sheets ofwood pulp after being steeped in an alkali solution and pressed toremove the excess solution are usually subjected to 10 a shredding orgrinding treatment to reduce the alkali cellulose to a finely dividedstate suitable for subsequent treatment. This shredding operation isusually performed in a shredding or mixing machine having mixing bladesmounted on horizontal rotary shafts with a hopper located above themixing blades, whereby the charge is introduced into the shreddingmachine.

During the operation of the shredder there is a decided pocketing actionof the alkali cellulose in the corners of the hopper of the shreddler,which pocketing action increases with the size of the shredder charge.This pocketing action results in an incomplete and non-uniform shreddingwith the result that relatively large pieces of cellulose 26 pass on tothe subsequent operations. The presence of relatively large pieces ofcellulose in the xanthating operation results in an improper andincomplete action of the xanthating agent.

These improperly xanthated pieces do not dis- 30 solve properly andcause serious difficulty, par-,

ticularly at the time of filtration of the viscose solution. I l

To prevent these objectionable results due to pocketing, it has been thepractice to restrict the size of the charges introduced into theshredder and to give the hopper of the shredder frequent manualcleanings. Restricting the size of the charges necessitates an increasednumber of charges for the production of a given quantity of viscose withconsequent increase in the cost of overhead and handling chargesanddecrease in efficiency of the machine as a unit of production.

The time required for manual cleaning holds up the operation of themachine during the cleaning process and causes considerable difficultyin maintaining the uniformtemperature necessary in the production ofhigh-grade viscose.

I have found that by so constructing the hopper 01' the shredder thatthere are no sharp corners or pockets where an accumulation of chargematerial can take place, the pocketing actionis prevented or inhibited,with the consequence that alarge increase can be made in the quantity ofthe hopper charge, thus resulting in an increase in production ofuniformly shredded material;

It is therefore an object of this invention to so construct the hopperof a shredding or mixing machine as to substantially prevent pocketingof the material being worked, thus providing a more uniform product andpermitting larger charges 5 of material being properly worked in themachine.

The above and other objects will appear from the following description,appended claims and accompanying drawing forming a part of thisspecification and in which: 10

Figure 1 is a front elevation of a shredding machine with the troughtilted to discharging position.

Figure 2 is an enlarged view of one of the fillets shown in the hopperin Figure 1, at right angles 15 to the position of the fillet in Figure1.

Figure 3 is a fragmentary sectional View on line 33 of Figures 1 and 2showing part of the trough and hopper and one of the fillets.

Figure 4 is a perspective view illustrating the 20 general shape of thespace occupied by a corner fillet.

Referring to the drawing which discloses one embodiment of the inventionand wherein like reference numerals designate like parts, the ref- 25erence numeral 1 designates the base of an existing type of shreddingmachine on which is mounted a trough 2, the upper portion 3 of whichconstitutesa hopper functioning as a res ervoir not only to supply orfeed the material 30 into the zone of action of the shredder but also toretain at least an appreciable quantity of the material after it hasbeen shredded. ,The trough and hopper constitute a. box-likeconstruction whose normal position during operation is at 3approximately right angles to that shown in Figure 1, with the top ofthe hopper in horizontal position. The trough 2 is provided withcircular curved portions 4 and 5 past which respectively sweep theshredding or mixing blades 6 40 and 1 suitably mounted in the trough onhorizontal shafts.

The four corners of the hopper are provided respectively with thefillets 8, 9, l0 and H (Figure 1). 45

The fillet 8, like the others, is formed by means of a front plate l2having its side edges 13 and I4 welded to the hopper as shown. As thewall of the particular hopper 3 illustrated contains an offset l5(Figure 2) the front plate I 2 50 is provided with an extension .l6 tobe warped to fit into the offset IS in .the wall'of the hopper. Theupper partof the face of the fillet formed by the front plate I2overhangs the trough 1 and slopes inwardly as it extends downwardly 55until it vanishes at H. To enclose the space between the front plate l2and the corner of the hopper, a top plate I8 is welded in place aroundits edges to the hopper and the front plate if, as shown in Figure 2.

Figure 4 illustrates the general shape of the space occupied by a cornerfillet. Where the fillets are made of separate cast inserts, they may bemade of the shape illustrated in Figure 4, but where the fillets aremade of sheet metal welded in place as described concerning Figures 2and 3 they would consist only of the front plate I! and the top plate ISwithout any rear portion at 23.

While it is not to be considered as limitative of this invention, thefollowing example will serve to illustrate a practical application-ofthe invention:

An existing shredder of the type illustrated in the drawing and having acapacity of 200 gallons, with the internal length of the hopper being 52inches and its width 42 inches and the depth to the bottom of the trough43 inches, was provided with fillets as shown. The points is and 20(Figure 2) at the upper sides of the fillet are located 14 inches fromthe corner 2| of the hopper. The upper front edge 22 of the fillet is 8inches from the corner 2|. A shredder modified with fillets as shown anddescribed is capable of handling a batch or charge of 1000 pounds ofalkali cellulose and producing a satisfactorily shredded product,whereas the average charge which can be properly handled by anunmodified shredder hopper is approximately 600 to 700 pounds.

Shredders employed prior to this invention and which were not equippedwith fillets made in accordance with this invention unless manuallycleaned at frequent intervals produced a partially shredded materialwhich frequently amounted to as much as 1% of the charge, whereas with ashredder constructed in accordance with this invention, 1. e. thefillets in place, uniform shredding is obtained even when the charge isincreased 50 to 75% over that used in the prior apparatus. Moreover,better shredding is obtained with a large charge in the filletedshredder than with a small charge in a non-filleted shredder.

The hopper may be constructed in various ways so as to have no sharpcorners or pockets where accumulation of the charge material can takeplace. The hoppers of existing shredders can be modified by means offillets made in various ways,

depending upon the type of hopper. The fillets may be made, for example,of sheet metal welded in place as shown in the present drawing or ascast inserts bolted or otherwise secured in place. If desired, thehopper can be originally constructed with integral cast fillets orconstructed of a shape having no corners or pockets where accumulationof charge can take place.

Since it is obvious that various changes and modifications may be madein the above description without departing from the nature and spiritthereof, this invention is not restricted thereto except as defined inthe appended claims.

I claim:

1. A shredder for producing substantially uniformly comminuted alkalicellulose comprising a shredding trough normally open only at the topthereof and containing a shredding mechanism to continuously operate ona batch of alkali cellulose under treatment to comminute the same,

and a hopper open at the bottom thereof and having a plurality of sidesforming a plurality of corner locations disposed in cooperativerelationship with said shredding mechanism and trough constituting areservoir which supplies the alkali cellulose to be shredded andreceives and retains at least a portion of the alkali cellulose after ithas been shredded, said hopper having a fillet of substantial size ineach of said comer locations to prevent pocketing of the alkalicellulose being shredded, each of said fillets having a frontal facewhich slopes inwardly in a downward direction and terminates in a pointadjacent the top of the said trough.

2. A shredder for producing substant allv fin formly comminuted alkalicellulose comprising a shredding trough normally'open only at the topthereof and containing a shredding mechanism to continuously operate ona batch of alkali cellulose under treatment to comminute the same, and ahopper open at the bottom thereof and having a plurality of sidesforming a plurality of comer locations disposed in cooperativerelationship with said shredding mechanism and trough constituting areservoir which supplies the alkali cellulose to be shredded andreceives and retains at least a portion of the alkali cellulose after ithas been shredded, said hopper having an overhanging fillet ofsubstantial size in each of said corner locations to prevent pocketingof the alkali cellulose being shredded, each of said fillets having afrontal face which slopes inwardly in a downward direction andterminates in a point adjacent the top of the said trough.

ADOLPH F. WENDLER.

